Herman was born in Columbia City, Indiana and raised in Fort Wayne, Indiana, attending Concordia Lutheran High School. At Concordia, Herman participated in various sports including football, track and field, and cross country. He also competed in wrestling for one month in his sophomore year before being expelled from the school. After taking his GED as a junior and spending a year at IPFW, Herman transferred to Indiana University at Bloomington, which has a Division I wrestling program. Despite having basically no high school wrestling experience, Herman competed for Indiana as a walk-on and excelled, competing for three full years and part of a fourth year. He red-shirted his first season which was from 2003–04 and held an impressive 28-9 record in his second season. He then claimed the exclusive starting role in his third season, holding a 28-16 record and qualifying for the NCAA tournament, in which he went 2-2. In a 2006 pre-season ranking, Herman was placed as high as eighth in the nation. In his fourth season Herman started off the season flawlessly, winning a tournament in November, but left a week later with no explanation for his departure but graduated from the university with a degree in general studies. Herman began training in mixed martial arts after watching one of his former college teammates train in the rising sport. He married Madeleine Atchley in March 2014. They live on a farm and are expecting their first child, a boy. [4]

Following a 2–0 amateur career, Herman made his professional mixed martial arts debut on December 31, 2006. He quickly amassed an undefeated 11–0 record, fighting 10 times throughout 2007, and went 13-0 before actually joining an MMA gym and officially begin training.

In 2010, Herman became entangled in a lawsuit with Bellator[6] that kept him out of action in the United States for just over a year. Once the legal issues were settled, Herman was scheduled to face Ricco Rodriguez at Bellator 31[7] but Rodriguez pulled out of the fight due to a knee injury.[8] Michal Kita stepped in, and served as Rodriguez's replacement.[9] Herman defeated him via first round submission.

Herman received his second loss after being disqualified for illegal knees to Rameau Thierry Sokoudjou. Herman then faced Yoshihiro Nakao at World Victory Road Presents: Soul of Fight.[10] He won the fight via decision, the first fight in his career to go the distance.

When Brock Lesnar pulled out of his main event fight with Junior dos Santos, Jon Olav Einemo's original opponent, Shane Carwin, stepped up to replace Lesnar against dos Santos. Herman instead fought fellow UFC newcomer Einemo. Herman defeated Einemo via TKO (punches) at 3:19 of round 2 in a back and forth bout that earned Fight of the Night honors.[13]

Herman was scheduled to face Mike Russow on October 8, 2011 at UFC 136.[14] However, the bout was cancelled after Herman failed his preliminary drug test in which he tested positive for marijuana and steroids. Herman denies using the prohibited substances.[15]

Herman next faced Antônio Rodrigo Nogueira on October 13, 2012 at UFC 153.[18] Herman was submitted by Nogueira via armbar in the second round, receiving the first submission loss of his career.

Herman tested positive for marijuana for the second time after failing his post-fight drug test for UFC 153. He was suspended for six months and ordered to undergo treatment.[19] The suspension was lifted in April 2013.[20]

Herman was expected to face Shane del Rosario on July 6, 2013 at UFC 162.[21] However, del Rosario was forced off the card due to injury and replaced by Gabriel Gonzaga.[22] Herman lost the fight just 17 seconds into the first round by TKO. After losing four fights in a row, Herman was released from the UFC.[23]

Herman was expected to face Kalib Starnes at Titan FC 28 on April 25, 2014.[25] However the event was delayed until May 16, 2014.[26] He won the fight via unanimous decision.

Herman was expected to face Walt Harris at Titan FC 30 on September 26, 2014.[27] However Harris was forced out of the bout with a back injury and the fight was then rescheduled to take place at Titan FC 32 on November 20, 2014.[28] However the bout was scrapped after Harris re-signed with the UFC.[29] Herman was then expected to face Jon Madsen for the Titan FC heavyweight championship at the event.[30] On November 4, 2014 it was announced that Titan FC 32 would be postponed to December 19, 2014 and will be moved from Augusta, Georgia to Lowell, Massachusetts[31] Herman subsequently pulled out of the bout due to an injury.

On January 19, 2015 Herman was arrested in the early morning in Indiana, allegedly after leading police on a chase. Herman faces three felony charges, including resisting law enforcement with a vehicle and battery against law enforcement, and a misdemeanor charge of child neglect. His infant child was in the vehicle when he fled and resisted.

According to an incident report issued by the Dekalb County Sheriff Department, Herman was speeding on I-69 with no headlights or taillights on. When officers attempted to pull him over, Herman initially refused to pull over before stopping at a gas station, the report states.

According to the report: “David exited his vehicle and approached Officers in an aggressive manner. David was given multiple warnings to get on the ground and failed to comply. David had to be tased in order to be taken into custody. An infant and adult female were also present in the vehicle.”[32][33]

Herman's wife Madeleine claims that the police used excessive force and that Dave was attacked and tased by the police officers for not submitting without question. She also claims they opted to wait before pulling over so they could find a well-lit area for their own safety. She filmed the arrest and is demanding that Dave be released and the officers be charged.[34]